This project is designed to control the breeding cycle in sheep and to breed ewes out of season. Data exists that indicated the rhythmic secretion of the pineal hormone, melatonin, regulates seasonal breeding in a variety of mammals, including sheep. Sheep usually breed in the fall when elevated levels of circulation melatonin are longer (mimicking the longer night). During the spring when levels of melatonin are shorter, sheep enter a period of anestrus. Elevated levels of melatonin will be maintained by daily feeding of melatonin.